Stack 1D arrays as columns into a 2D array.
Take a sequence of 1D arrays and stack them as columns to make a single 2D array. 2D arrays are stacked asis, just like with hstack. 1D arrays are turned into 2D columns first.
Parameters:  tup : sequence of 1D or 2D arrays.


Returns:  stacked : 2D array

Notes
The function is applied to both the _data and the _mask, if any.
Examples
>>> a = np.array((1,2,3))
>>> b = np.array((2,3,4))
>>> np.column_stack((a,b))
array([[1, 2],
[2, 3],
[3, 4]])